1. Field of the Invention
The present invention relates to an electronic part insertion apparatus for inserting a large number of the same kind of electronic parts having leads, such as ICs (integrated circuits), into a printed circuit board to perform a heating test, etc., of the electronic parts.
2. Description of the Related Art
In a conventional electronic part having leads, such as an IC, the IC is formed to have a function guarantee maximum temperature of 60.degree. C. to 70.degree. C. in an ambient temperature, and is formed practically to have a certain safety factor (margin) with respect to that temperature. However, defective or nearly defective ICs having defects or an inferior reliability sometimes occur. Therefore, before actually packaging the ICs on a printed circuit board, the ICs are usually tested by a high temperature heating test (so called "burn-in test") to confirm their acceptability. The high temperature heating test is performed under adverse conditions after housing many ICs of the same kind in a constant temperature oven (thermostatic chamber).
Namely, a number of ICs, for example, 100, are inserted into a testing printed circuit board directly or through sockets. A plurality, for example, ten, of the printed circuit boards are stacked one upon another in a box-like shelf, the shelf being stacked in the thermostatic chamber. Connectors of the printed circuit boards are engaged with connectors provided inside the thermostatic chamber, and a temperature in the thermostatic chamber is increased to a predetermined high value (for example, 120.degree. C.). A voltage (for example, 5 V), which is equivalent to the voltage actually used by the IC, is applied to respective ICs to cause the ICs to generate heat, and this state is maintained for a predetermined period of time (for example, 72 hours or 48 hours) to complete the high temperature heating test. Through this high temperature heating test, ICs having certain defects will be broken or damaged, and are thus rejected. After the heating test, a function test is performed on the ICs by a tester to determine acceptable and not acceptable ICs, and the accepted ICs are then packaged on a printed circuit board.
When carrying out the high temperature heating test according to the prior art on the same kind of electronic parts such as ICs having leads, in most cases a worker must wear a grounding band when manually inserting the ICs one by one into a printed circuit board directly, or through sockets mounted on the printed circuit board. Therefore, according to the prior art method mentioned above, a long time is required for manually inserting the ICs one by one into the testing printed circuit board, and the work efficiency is seriously affected. Also, although the worker is grounded when inserting the ICs, static electricity tends to flow from the body of worker to the ICs and has an undesirable effect on the ICs, because the worker's hands must directly touch the ICs.